How to Figure Concrete Yards
- 1). Measure the length and width of the walkway you will be pouring. Typically, a service walk should be 3 feet wide and the length will be as long as you need it to be.
- 2). Multiply the length times the width of the walkway and divide that answer by 81 to determine the number of cubic yards you'll need for a slab that is 4 inches thick. For example, if your walkway will be 3 feet by 12 feet, multiply 3 by 12 and divide by 81 for an answer of .444444. If you only want the walkway to be 3 inches thick, use a factor of 75 rather than 81 in this formula.
- 3). Round your answer up to the next whole number to determine how many yards of concrete you need to order. Using the example of a 3-by-12-foot walkway poured to a 4-inch thickness, you would round .444444 up to 1 yard of concrete.